Regenerative internal combustion engine

Abstract

A highly efficient regenerative reciprocating internal combustion engine is disclosed. The regenerator captures the unutilized heat normally expelled with the exhaust products of such an engine and transfers it to fresh working fluid at the appropriate time in the next engine operating cycle to reduce the quantity of fuel which must be burned, resulting in an increase in engine efficiency. This is accomplished through the use of a permeable, movable heat exchanger located between the piston and the cylinder head. This regenerative technique can be applied to both two and four stroke Diesel cycle and Otto cycle engines. It can also be employed in ported (i.e. valveless) engines. The hot combustion region can be located between the cylinder head and the regenerator or between the piston and the regenerator. These regenerative devices and processes greatly improve the thermal efficiency of conventional internal combustion engines, while providing power outputs similar to conventional engines of the same displacement, greatly reducing hydrocarbon and carbon monoxide emissions, and utilizing much the same hardware. In addition, the regenerative internal combustion engine places reduced heat loads on engine components, is operable at lower peak temperatures (with thermal efficiencies and power still comparable to conventional engines), and is better able to utilize high temperature materials which can reduce heat loss to engine cooling systems.

We claim: 
     
       1. In a thermally regenerated reciprocating cyclic internal combustion engine having a rotating power output shaft composed of a number of similar working units, each working unit comprising (1) a cylinder closed at one end by a cylinder head, with a number of intake valves to draw cool fresh air into the cylinder, and a number of exhaust valves to exhaust the spent combustion gases from the cylinder; (2) a first means for opening and closing said intake and exhaust valves in a predetermined manner once in each engine cycle; (3) a piston inside the cylinder moving along the axis of the cylinder in a reciprocating manner toward and away from the cylinder head between the top dead center position closest to the cylinder head and the bottom dead center position furthest away from the cylinder head, said piston being connected to the power output shaft by a second means which translates the reciprocating motion of said piston to rotation of the power output shaft; (4) a thermal regenerator inside the cylinder between the cylinder head and the piston, capable of being moved in predetermined cyclic reciprocating motion along the axis of the cylinder and comprising a permeable core and other structure, to absorb heat from the hot combustion gases when moved in one direction, and to transfer the absorbed heat to the cool fresh air when moved in the opposite direction; (5) a third means for imparting a predetermined periodic motion to said thermal regenerator; (6) an injection means for injecting combustible fuel into the cylinder; and (7) an ignition means for igniting the mixture of said air and said fuel in the cylinder: the thermal regenerator in which the permeable core comprises multiple layers of fabric woven from high temperature resistant ceramic fiber yarn.   
     
     
       2. In a thermally regenerated reciprocating cyclic internal combustion engine having a rotating power output shaft composed of a number of similar working units, each working unit comprising (1) a cylinder closed at one end by a cylinder head, with a number of intake valves to draw cool fresh air into the cylinder, and a number of exhaust valves to exhaust the spent combustion gases from the cylinder; (2) a first means for opening and closing said intake and exhaust valves in a predetermined manner once in each engine cycle; (3) a piston inside the cylinder moving along the axis of the cylinder in a reciprocating manner toward and away from the cylinder head between the top dead center position closest to the cylinder head and the bottom dead center position furthest away from the cylinder head, said piston being connected to the power output shaft by a second means which translates the reciprocating motion of said piston to rotation of the power output shaft; (4) a thermal regenerator inside the cylinder between the cylinder heat and the piston, capable of being moved in predetermined cyclic reciprocating motion along the axis of the cylinder and comprising a permeable core and a cylindrical skirt for structural strength, for reducing gas flow around the regenerator and for providing a bearing surface against the cylinder wall, to absorb heat from the hot combustion gases when moved in one direction, and to transfer the absorbed heat to the cool fresh air when moved in the opposite direction; (5) a third means for imparting a predetermined periodic motion to said thermal regenerator; (6) an injection means for injecting combustible fuel into the cylinder; and (7) an ignition means for igniting the mixture of said air and said fuel in the cylinder: the thermal regenerator in which the cylindrical skirt seals apainst the cylinder wall by means of multiple grooves and lands formed in its outer surface.   
     
     
       3. In a thermally regenerated reciprocating cyclic internal combustion engine having a rotating power output shaft composed of a number of similar working units, each working unit comprising (1) a cylinder closed at one end by a cylinder head, with a number of intake valves to draw cool fresh air into the cylinder, and a number of exhaust valves to exhaust the spent combustion gases from the cylinder: (2) a first means for opening and closing said intake and exhaust valves in a predetermined manner once in each engine cycle; (3) a piston inside the cylinder moving along the acis of the cylinder in a reciprocating manner toward and away from the cylinder head between the top dead center position closest to the cylinder head and the bottom dead center position furthest away from the cylinder head, said piston being connected to the power output shaft by a second means which translates the reciprocating motion of said piston to rotation of the power output shaft; (4) a thermal regenerator inside the cylinder between the cylinder head and the piston, capable of being moved in predetermined cyclic reciprocating motion along the axis of the cylinder and comprising a permeable core and a cylindrical skirt for structural strength, for reducing gas flow around the regenerator and for providing a bearing surface against the cylinder wall, to absorb heat from the hot combustion gases when moved in one direction, and to transfer the absorbed heat to the cool fresh air when moved in the opposite direction; (5) a third means for imparting a predetermined periodic motion to said thermal regenerator; (6) an injection means for injecting combustible fuel into the cylinder; and (7) an ignition means for igniting the mixture of said air and said fuel in the cylinder: the thermal regenerator in which the cylindrical skirt seals against the cylinder wall by means of a close fitting groove in its outer surface which holds an elastic ring which presses lightly against the cylinder wall.